This engine has been flushed twice for 6 hours with citric acid, and continues to do this. This is for the crowd that think a rusty engine can just be treated by flushing with a garden hose and pretending the problem goes away. This particular engine feeds the coolant filter from the block drains. Anything, sink or swim, is going to end up going in here. I drilled out the restrictor on the new filter that replaced this one to get a little more velocity through those hoses to more easily catch this stuff. Exit is plumbed directly to the water pump, so I don't want velocity and suction to be so much that it can pull stuff through the media or disturb the sediment resting at the bottom. Entry hoses are 1/2", and exit hose is 5/8" to match the water pump inlet. Very capable of going to suction if not careful. From the looks of the filter media, it seems most if the sediment falls out of the coolant and finds the filter canister a good place to settle more than gets caught in the filter media. The pleats were not torn. I forced them apart to get a good look at the trash in there.